A. Field of the Invention
The invention relates generally to the field of sugar-sensitive reagents, and in particular to a class of boronic, arsenious, germanic and telluric acid derivatives that exhibit quantitative sensitivity to the presence of certain polyhydroxyl compounds.
B. Description of the Related Art
Reactions of glucose and other monosaccharides play a virtually universal role in the metabolic pathways of living organisms. Chemical breakdown of monosaccharides provides a source of energy during periods of activity, while absorption and concatenated storage of these same substances takes place during quiescence. Detecting the presence and concentration of biologically important sugars in mixed aqueous solutions is necessary in a variety of industrial, medicinal and research contexts, ranging from assessing the status of fermentation processes to monitoring blood glucose levels in individual suffering from diabetes.
A number of sugar-detection methods are presently in use, but all present certain disadvantages. Enzyme sensing systems offer specificity, but contain labile protein complexes that denature upon exposure to harsh conditions (such as those encountered during steam sterilization). Refractive index methods of sugar sensing do not require special reactive conditions, but are nonspecific with respect to the chemical identity of the sugar, and tend to exhibit cross-sensitivity to other compounds, such as proteins.
The present invention makes use of the well-known ability of boric acid (and the borate ion) to bond covalently to polyols containing vicinal hydroxyl groups. Borate columns are frequently used to separate different sugars, which bind to such a column with differing strengths depending on the sugars' molecular structures; glucose typically binds most strongly of all common monosaccharides to such columns. The covalent bond formed during binding resists the influence of most contaminants, but is nonetheless reversible, thereby permitting elution with borate buffer.
Japanese Patent No. 81 116,754 describes the synthesis of dyes with diazotized m-aminophenylboronic acid (APB) and naphthol derivatives. These dyes bind to textiles containing hydroxyl groups, and exhibit absorbance maxima around 500 nm. A recent publication [Burnett, Peebles & Hageman, 96 Biochemical and Biophysical Research Communications 157 (1980)] discloses a fluorescent dye derived from APB and dansyl chloride, which was synthesized to bind to bacterial cell surfaces. At pH 8.5, the dye appears to have an absorbance maximum around 350 nm, and an emission maximum around 550 nm. Neither reference suggests the use of the compounds disclosed therein to detect or measure the presence of specific polyhydroxyl compounds.